Thank you Subir Bandyopadhyay for this explanation, but my point is that sometimes it is really different and it is not published before (mostly in varieties and subspecies) and they don't accept it , while they accept others that have the same case. This is really confused because in Europe it has been accepted, so why is this contradiction,don't they follow the same principles? I can't say that in Europe the scientists when they accept it means that they are weak and they have no knowledge in orchids Taxonomy. There is a gap that need to be explain.

The rules for giving scientific names for plants (and orchids in particular) is established and regulated by International Code of Nomenclature for algae, fungi, and plants. You can find the latest valid edition here http://www.iapt-taxon.org/nomen/main.php There can be some minor changes after Botanical Congress in China in summer this year, but likely not in rules for giving scientific names, because they are pretty conservative and well developed.

Dear Khodr,

Kindly clarify your question.

Can you cite your problem?

I am giving you answer in a way I have understood. ICN never gives  guidelines to the authors regarding the status of  a new taxon. So a new species of one author might be a variety to another author or  vice versa. Authors might describe a new taxon overlooking that it has already been described. Good journal try to evaluate the new taxon with the help of the reviewers but it is not possible for them to have experts in all the plant groups. So a new taxon published in good journal might not always be a good one.The names obviously need to be validly published following the rules of iCN. In good journals, however,  such mistakes are very rare. Moreover, the names will might be illegitimate in the form of later homonym, isonym, etc.

 Thank you Subir Bandyopadhyay for this explanation, but my point is that sometimes it is really different and it is not published before (mostly in varieties and subspecies) and they don't accept it , while they accept others that have the same case. This is really confused because in Europe it has been accepted, so why is this contradiction,don't they follow the same principles? I can't say that in Europe the scientists when they accept it means that they are weak and they have no knowledge in orchids Taxonomy. There is a gap that need to be explain.

Kindly explain to me the sentence "...it is not published before (mostly in varieties and subspecies) and they don't accept it , while they accept others that have the same case'. 

It means that it is not the same plant and published with a new name and the publisher  did not know that the same plant was published by another one before him with different name. 

In such cases just reduce the names as new synonyms with proper justification.

Yes i know but if we do this we will not be able to distiguish them by name

There will be an accepted name  with a type. The synonym will also have its own type.

Dear Khodr Addam, can I assume that when you say "Kew" you are talking about the Kew Monocot Checklist ? This website is maintained by R. Govaerts, who is not an authority on orchids, but gets advice from people who are authorities. On the website Home page, 2nd paragraph, there is a button labelled "Reviewers". Click this to go to the list of experts who review entries for the list.

There have been a lot of new orchid species published recently, and also a large number of taxonomic changes. Govaerts and the reviewers cannot keep up. They are currently about 3-4 years behind schedule for updating the list. So it is possible that a species (or taxon) name does not appear because it hasn't been reviewed yet, or there is uncertainty about its status. 

If the taxon name appears on the list but is in the "Not Accepted By", drop-down menu, then it means that either (a) the name has not been accepted by the reviewer (could be any number of reasons), or (b) the taxon was previously accepted (the drop-down menu will tell you where and when), but the genus name has been changed, so the name is no longer considered up-to-date.

You can always try emailing Govaerts with your questions .... he is usually good about replying.

Hello

the ICBN is for nomenclature. It determines if a new name is validly published, if it is a correct name. That's it. Taxonomy is another story. Everyone is free to believe that a valide and correct taxon is just a synonym of an earlier taxon. You are allowed to believe that Homo neanderthalensis and Homo sapiens are the same species. The correct name of that group will be H. sapiens, this is what nomenclature says. Similarly you are allowed to think that Ophrys apifera is the correct name for dozen of microtaxa (O. elatior, O. fuciflora, O. scolopax, etc.)

marc.

Dear Khodr Addam,

I know some exemple for asian and american orchids, witch have different accepted names by Kew and Missouri BG or Ecuador.

The conflicts for European orchids are not very often...

If you send for an expert opinion,then only they will answer your queries.But youshould find a right person for the job.

 V.s. Ramachandran  can you define for me what is an expert in orchid's taxonomy, because all the famous taxonomists in this field (right persons for the job) have a lot of conflicts and different opinions, so who you are going to follow.